Insurance Company v. The Treasurer was a United States Supreme Court case that dealt with the issue of whether a state could tax the income of an insurance company. The insurance company argued that the tax was unconstitutional because it violated the Contract Clause of the United States Constitution. The Court held that the tax was constitutional because it was a valid exercise of the state's power to tax. The Court reasoned that the tax was not a violation of the Contract Clause because it did not interfere with the insurance company's contractual obligations. The Court also held that the tax was not a violation of the Due Process Clause because it was a reasonable exercise of the state's power to tax. The Court concluded that the tax was a valid exercise of the state's power to tax and was not a violation of the Constitution.

In Insurance Company v. The Treasurer, the Supreme Court was asked to decide whether a state statute that required insurance companies to pay taxes on their capital stock violated the Constitution of the United States. In a 5-4 decision, Justice Field wrote for the majority and held that it did not violate any constitutional provision. However, in his dissenting opinion, Justice Swayne argued that such taxation would be an unconstitutional burden on interstate commerce because it would place insurance companies from other states at a disadvantage compared to those within the taxing state. He further argued that this type of tax could lead to multiple taxation by different states if each imposed its own rate and thus create an undue burden on interstate commerce which is prohibited by Article I Section 8 Clause 3 of the Constitution.